My iPod has been having trouble getting a good wifi signal.

My iPod has had very weak singals to wifi latley. I have to stand right beside my router for the signal to pick up. I know it's not my router because my friend with the same iPod as me (8GB 4 gen iPod Touch) and has no problems connecting to the wifi. I don't know if this matters but I did drop it the day that it started acting up. If anyone can help please do.